Open Historical Map supports a mixed-copyright concept. The license=* tag is used to indicated the licensing on an object-by-object basis. The user should pick the highest level object they are editing and place a suitable tag on it.
CC0 is strongly recommended; CC0 is a "No Rights Reserved" copyright that is equivalent to public domain. Care must be used in sourcing to insure that CC0 is appropriate.
Copyright and Data Attributions
OHM data contribution that require attribution (e.g. CC-BY) should be identified here: OHM/Contributors.
- Bundesamt für Landestopografie Schweiz [Siegfried map of Switzerland]